/**
 * Created with IntelliJ IEDA.
 * Description:
 * User:86186
 * Date:2022-05-19
 * Time:22:37
 */
class a{
    public a eat(){
        return new a();
    }
}
//子类的返回值和父类是父子类关系也可以【协变类型】
class b extends a{
    public b eat(){
        return new b();
    }
}


public class Demo {


}
